A case of psoriatic arthritis with type I cryoglobulinemia associated with multiple myeloma

AbstractA 70-year-old Japanese male with psoriasis vulgaris was admitted for neck, elbow, knee, ankle and buttock pain. He had chilblain-like rashes on the face and auricle and lower extremity purpura. He was diagnosed with psoriatic arthritis (PsA) according to enthesitis detected by musculoskeletal ultrasound. Blood examination showed IgG-κ type M protein and cryoglobulin. Skin biopsy of lower extremity showed thrombus in the artery. Bone marrow aspiration demonstrated no proliferation of plasma cells initially, and he was considered with monoclonal gammopathy of undetermined significance (MGUS). Two months later, plasma cell clonal expansion was detected in the bone marrow, and he was diagnosed with PsA and type I cryoglobulinemia associated with multiple myeloma. PsA may be a risk factor for MGUS. We described a case of PsA complicated with MGUS, which developed to multiple myeloma.